The present invention relates to door hinges and particularly to gravity swing door hinges.
A gravity swing door typically includes a door jamb mounting structure and a pivot post for supporting a door panel. A cam arrangement couples the jamb mounting structure and the pivot post and operates to bias the door to a closed position. The weight of the door bears against the jamb mounting structure through the cam arrangement. The force of gravity on the door brings a cam roller into a biasing depression on an inclined cam surface. When the cam roller is in the biasing depression, the door is in its closed position. Pivoting the door away from its closed position brings the cam roller out of the biasing depression and upward onto the inclined cam surface. The door is thereby raised slightly. Releasing the door allows the door to drop and pivot back to its closed position as the cam roller returns to the biasing depression.
A gravity swing door hinge is exposed to potential damage during use. The cam arrangement, pivot post and jamb mounting structure are generally exposed. These exposed inner workings of the hinge may be damaged when large heavy objects pass through the door and contact the hinge. Also, foreign objects can foul or damage the cam arrangement.
A gravity swing door presents a risk of injury to persons working near the door hinge. Because the entire weight of the door rests against the cam surface, a hazardous pinch-point for fingers and hands exists between the cam surface and the moving roller bearing. When a gravity swing door pivots, the door and the pivot post move up and down with respect to the jamb mounting structure. When the door moves upward toward the jamb mounting structure a person's hand or fingers could be trapped and injured between the top edge of the door and the jamb mounting structure.
Gravity swing doors generally have a limited range of motion. Because gravity swing doors are typically used in high traffic areas where large articles are brought through the door, it is desirable that the door swing widely open. If the door does not have a broad pivot range, movement through the door is limited. For example, if the door swings 90 degrees on each side of a plane containing the door in its closed position, a path as wide as the door jamb must be followed even after passing through the door jamb. If the door swings greater than 90 degrees, however, the path is widened immediately past the door jamb and greater mobility is achieved. Some door hinges mount at the corner of a door jamb and permit a greater range of pivot motion on one side of the door jamb. However, motion is limited on the opposite side of the door jamb. Also, the corner mount hinge does not position the door, when closed, within the opening defined by the door jamb. A hinge mounted flush to the door jamb surface does position the door within the door jamb opening. Accordingly, it is desirable that a gravity swing door hinge mount flush to the door jamb and provide greater than 90 degree pivot motion on both sides of a door jamb. Such a gravity swing door hinge would provide greater mobility for persons passing through the door while positioning the door within the door jamb opening.